1. Field of the Invention
The present invention relates generally to mobile telecommunications, and in particular to PDSN load optimization in mobile telecommunications networks.
2. Description of the Invention
CDMA2000 is a 3G mobile telecommunications standard that among other thing provides mobile Internet Protocol (IP) services to mobile nodes (MNs).
FIG. 1 illustrates a simplified CDMA2000 network 100 that comprises a Packet Data Serving Node (PDSN) 113, and a Packet Core Function (PCF) usually co-located with a Base Station Controller (BSC) 112. The PDSN 113 acts as a kind of gatekeeper, deciding what MNs are allowed to use services and access the network, and is the gateway for traffic to the interconnecting network 114, to which for instance entities such as servers and other MNs that the MN 111 desires to contact. In the BSC/PCF 112, the BSC among other things establishes the traffic channel (TCH) 121 for the MN 111 to use and the PCF decides which PDSN to send the traffic through. A Packet Core Network Manager (PNM) 115 is responsible for management of the packet core network, comprising among other things the PDSN 113, and is thus informed of for example the load of the PDSN 113. Note that the PNM 115 is not necessarily connected to the PDSN 113 the way it is shown in FIG. 1.
When an authorised mobile node (MN) 111 wants to use the network 100, in the BSC/PCF 112, the BSC sets up a traffic channel (TCH) 121 with the MN 111, and the PCF sets a R-P connection 122 with the PDSN 113. The PDSN 113 and the MN 123 establish a PPP connection 123.
The MN 111 is not obliged to transmit or receive continuously for the PPP connection 123 to remain established and the PDSN 113 is likely to have a plurality of PPP connections with various MNs. In order to get rid of PPP connections that have not been used in a relatively long while, the PDSN 113 has a PPP inactivity timer for each PPP connection. When the PPP inactivity timer expires, the PDSN 113 terminates the PPP connection 123, which means that the MN 111 has to renegotiate a new PPP connection if it desires to be in connection with the PDSN 113.
It can be appreciated that it is important to have PPP inactivity timers, as there is a limited number of PPP connections a PDSN can support. Today, the PPP inactivity timer is a fixed value set by the network administrators or by the PDSN manufacturers. It can also be appreciated that a fixed PPP inactivity timer value is not efficient, as this value for example may be unnecessarily short when there is little load, i.e. few PPP connections, on the PDSN, and unnecessarily long when there is much load on the PDSN.
For these reasons, it would be advantageous to have a more flexible way to set the PPP inactivity timer. This invention provides such a solution.